1. Technical Field
The present disclosure relates to flexible printed circuit boards (FPCBs) and, particularly, to an FPCB for transmitting high speed signals.
2. Description of Related Art
FPCBs include a signal layer and a ground layer parallel to each other; a signal transmission line is formed in the signal layer. Copper foils are formed in the ground layer corresponding to the signal transmission line. High speed signals can be transmitted utilizing electromagnetic induction effect between the signal transmission line and the copper foils. Limited to a relatively small thickness of the FPCB, the distance between the signal layer and the ground layer is relatively small too, resulting in relatively small impendence. However, transmission of high speed signals requires large impedance.
Therefore, it is desirable to provide an FPCB that can overcome the above-mentioned limitations.